Main control relay (Master Control Relay), abbreviated as MCR. MCR Master relay command is used to control whether normal execution of the instruction in the region, equivalent to a connect and disconnect the “flow“ of the main switch. MCR instruction is not much used, S7-200 is no MCR instruction.
MCRA to activate the master relay instructions, MCRD to deactivate the master relays orders.
Open the master relays orders “MCR<“ in the MCR before you save the results of logical operations on the stack RLO (MCR), close the master relays orders “MCR>“ MCR saved out of the stack in the RLO. “MCR<“ and “MCR>“ used to indicate controlled temporary “power cord“ formation and termination.
MCR instructions can be nested, MCR the MCR can be another zone. MCR stack is a LIFO stack, allowing the maximum nesting depth of 8 levels.
MCR–I0.2 control, I0.2 and MCR MCR in the stack level of the same State. MCR bit is 1 when will perform Q4.0 coil MCR control area and MOVE instructions. MCR bit is 0 when Q4.0 is 0.